O-alkyl n, n&#39;-dialkyl phosphorodiamidothioates



United States Patent This is a division of application Serial No.162,954, filed Dec. 28, 1961, now Patent No. 3,251,675.

The present invention is directed to methods employing-and compositionscomprising O-alkyl 'N,N'-dialkyl phosphorodiamidothioates correspondingto the formula s NHR- Raj-11 \NHR In this and succeeding formulae, eachR represents a lower alkyl radical. The expression lower alkyl isemployed in the present specification and claims to refer to theradicals containing from lcarbon atoms, inclusive. These new compoundsare oily liquids or crystalline solid materials which are somewhatsoluble in many common organic solvents and of low soluibility in Water.The compounds are useful in methods where they or compositionscontaining the compounds are employed as plant growth control materialsfor the modification of the growth or the killing of many undesirableplant species.

The new compounds are prepared by reacting an 0- lower alkyl,phosphorodichloridothioate with ammonia or lower alkyl amines. Thus, thephosphorodichloridothioate reagent is reacted with ammonia or a loweralkyl amine, or successively with two different members of the groupconsisting of ammonia and lower alkyl amine, depending upon whether ornot it is desired to replace the phosphorus bound chlorine in thephosphorodichloridothioate reagent with the same or differentsubstituting moieties. Where two different amide moieties are introducedinto the molecule, the introduction of the first amide moiety resultsin'the production of an O-alkyl N-alkyl phosphoramidochloridothioateintermediate. The reaction conveniently is carried out in a liquidreaction medium such as methylene chloride, acetone, water, benzene andso forth. The reaction is somewhat exothermic and takes place smoothlyat the temperature range of from to 50 C. with the formation of thedesired product and ammonium chloride and/or amine hydrochloride ofreaction. The temperature may be controlled by regulating the rate ofcontacting the reactants and by external cooling. Good results areobtained when employing two molecular proportions of ammonia or aminereagent with each gram atom of phosphorus bound chlorine it is desiredto displace in the phosphorodichloridothioate reagent. Following thereaction, the desired product is separated and purified by conventionalprocedures.

In carrying out the reaction, gaseous ammonia and/or alkyl amine iscontacted in any convenient manner with the phosphorodichloridothioatereagent and preferably in a solvent as reaction medium. In analternative procedure, a aqueous solution of ammonia and/or alkyl amineis mixed and blended with the phosphorodichloridothioate reagent. Ineither case, the contacting of the reagents is brought about usuallyportionwise and with stirring and at a temperature of from 20 to 50 C.Following the contacting of the reagents, the mixture 3,309,429 PatentedMar. 14, 1967 is usually stirred for a short period to insure completionof the reaction. Upon completion of the reaction, the reaction productis washed with water to separate ammonium chloride or aminehydrochloride. It the reaction is carried out in a water-misciblesolvent, the washing step leaves the desired product as a residue. Ifthe reaction is carried out in one of the water-immiscible solvents, thesolvent may be removed by evaporation or vacuum distillation followingthe washing step to obtain the desired product as a liquid orcrystalline residue. 7

The following examples merely illustrate the invention and are not to beconstrued as limiting.

Example 1.O-ethyl N,N'-dibulyl phosphorodiamidathioate N-butylamine(87.6 grams; 1.2 moles) was added portionwise to 53.7 grams (0.3 mole)of O-ethyl phosphorodichloridothioate dispersed in 600 milliliters ofbenzene. The addition was carried out over a period of 1.5 hours and ata temperature of from 4 to 6 C. Stirring was thereafter continued andthe temperature of the reaction mixture maintained at from 5 to 10 C.for 16 hours to complete the reaction. The reaction mixture was thencooled to room temperature and the cooled mixture filtered to separatebutylamine hydrochloride. The innzene was removed from the filtrate byvacuum distillation and the residue dispersed in carbon bisulfide. Thecarbon bisulfide dispersion was then filtered and the carbon bisulfideremoved from the filtrate by evaporation under vacuum to obtain anO-ethyl N,N'-dibutyl phosphorodiamidothioate product as a liquid residuehaving a refractive index n/D of 1.4864 at 25 C., a specific gravity of1.0204 at 25 /25 C. and a sulfur content of 12.5 percent.

Example 2.O-pr0pyl N,N-diis0pr0pyl phosphorodiamidothioate reducedpressure to obtain an O-propyl N,N'-diisopropyl phosphorodiamidothioateproduct as a liquid residue. This product had a refractive index n/D of1.4830 at 25 C., a specific gravity of 1.0144 at 25/25 C. and aphosphorus content of 12.8 percent.

Example 3.O-butyl n-sec. butyl N'-is0butyl phosplzorodiamidothioateIsobutylamine (30 grams; 0.41 mole) was added portionwise with stirringto 41.4 grams (0.2 mole) of O-butyl phosphorodichloridothioate dispersedin 500 milliliters of benzene. The addition was carried out over aperiod of one hour and at a temperature of from 5 to 15 C. Sec.butylamine (31 grams; 0.425 mole) was then added portionwise withstirring to the above solution containing the O-butyl N-isobutylphosphoramidochloridothioate intermediate. This addition was carried outover a period of one hour and at a temperaure of 5 C. Upon completion ofthe reaction, the reaction mixture was filtered and the reaction mediumremoved from the filtrate by evaporation under reduced pressure toobtain an O-butyl N-sec. butyl N-isobutyl phosphorodiamidothioateproduct as a liquid residue. This product had a refractive index n/D of1.4803 at 25 C., a specific gravity of 0.9807 at 25/ 25 C. and aphosphorus content of 10.9 percent.

In exactly analogous manners, other products of the present inventionwere employed and are as follows:

Melting n/ D at Specific Phosphorodiamidothioates Point, 25 C. Gravityat O'methyl N, N-dibutyl 1.4950 1.0293 O-mcthyl N, N-diisopropyl 1.49731.0546 O-ethyl N, N-diisopropyl 25-28 O-butyl N, N-dibutyl 1.4815 0.9894

O-ethyl N, N-diethyl O-propyl N, N-dibutyl O-butyl N, N-diisopropylO-isobutyl N, N-di-tert-butyl O-isoprop l N, N -diisoprpyl.. O-isobutyN, N -diisopropyl. O-propyl N, N-di-sec. butyh. O-butyl N, N -diisobutylO-propyl N-isopropyl N-niethyl Oisopr0pyl N -sec. bntyl N-isopropylO-propyl N, N-di-tert-buty1 O-propyl N, N-dimethyl O-butyl N, N-dimethylO-propyl N, N-diethy O-butyl N, N-diethyl. O-propyl N, N-dipropylO-butyl N, N-dipropyl O-isopropyl N, N-dimethy O-isobutyl N, N-dimethylO-ethyl N, N-dipr0pyl O N-diisopropyl O-isopropyl N, N-dipropylO-isobutyl N, N-dipr0pyl O-sec. butyl N, N -dibutyl O-sec. butyl N,N-di-secbutyl... O-Sec. butyl N, N-dirnethyl O-see. butyl N, N-dipropyl.. O-nietliyl N, N -di-sec. butyl. O-pentyl N, N-dimetl1ylO-pentyl N, N-dipr0pyl O-Sec. butyl N, N-diethyl O-isobutyl N, -dicthylO-sec. butyl N-di-tert-butyl O-isopropyl N, N-diis0butyl. O-isobutyl N,N-diisobutyl O-isobutyl N, N -dibutyl O-scc. butyl N, N-diisobutyl.O-propyl N, N-diisobutyl O-isopentyl N, N-diisopropyl O-pentyl N,N-diisopropyl with a herbicide adj-uvant as a carrier therefor.

Thus,

the products can be dispersed on a finely divided solid such as talc,chalk, or a finely divided solid surface active dispersing agent such asbentonite and the resulting compositions employed as dusts. Also, suchmixtures can be dispersed in water with or without the aid of adispersing agent and the resulting aqueous suspensions employed assprays. In other procedures, the products are employed as activeconstitutents of solvent solutions, oil-inwater or water-in-oilemulsions, or water dispersions with or without suitable surface activedispersing agents. The new compounds or compositions containing suchcompounds are app-lied to the foliage of vegetation or dispersed in soilto expose plants, plant rootlets and plant parts, such as seeds, togrowth inhibiting and herbicidal amounts of the compounds. Inrepresentative operations, the application of the compounds to soil at adosage of pounds per acre gives excellent control of many plant speciesin pre-emergent applications such as millet, radish and wild oats, whilethe application of aqueous compositions containing 4,000 parts permillion by weight of the phosphorodiamidothioates gives excellentcontrol of the same species in such post-emergence applications.

The O-alkyl phosphorodichloridothioates employed as starting materialsin accordance with the teachings of the present invention are preparedin accordance with known procedures, wherein phosphorus thiochloride isreacted with a suitable alcohol. Good results are obtained whenoperating at temperatures of from 30 to C. and when employing thealcohol with a molar excess of the phosphorus thiochloride. Uponcompletion of the reaction, the desired starting material is separatedby fractional distillation under reduced pressure.

What is claimed is:

1. A compound corresponding to the formula s NHR My NHR wherein each Rrepresents lower alkyl.

2. O-ethyl N,N'-diethyl phosphorodiarnidothioate. 3. O-ethyl N,N'-diisopropyl phosphorodiamidothioate. 4. O-propyl N,N-diisopropylphosphorodiamidothioate. 5. O-butyl N,N-diisopropylphosphorodiamidothioate. 6. O-isobutyl N,N-diiso-butylphosphorodiamidothioate.

No references cited.

CHARLES B. PARKER, Primary Examiner.

BERNARD BILLIAN, Assistant Examiner.

1. A COMPOUND CORRESPONDING TO THE FORMULA